Per RFC 2616 section 9.4, we SHOULD return the content-length if possible on

Per RFC 2616 section 9.4, we SHOULD return the content-length if possible on
HEAD requests (even for CGI requests).  Also do it because it fixes the cause
of .37's demise.

This also fixes a condition seen on FreeBSD-4.6 where HEAD requests on CGI
scripts would hang because the OS would return EAGAIN in log_script_err
(via apr_file_gets).  Since we never read the script output, this caused
FreeBSD to not let us read stderr.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95633 13f79535-47bb-0310-9956-ffa450edef68